The investigators hypothesized that pancreatic cancer could be detected by measuring the changes in the early increase in blood supply (EIBS) found in the surrounding normal-appearing duodenal tissue. The investigators tested a device called Four-dimensional Elastic Light-Scattering Fingerprinting (4D-ELF). The device used in this study is considered investigational, which means it has either not been approved by the Food and Drug Administration (FDA) for routine clinical use or for the use described in this study. However the FDA allowed the use of this device in this research study.